The Data Model Resource Book, Volume 3: Universal Patterns for Data Modeling

Silverston c07.tex V2 - 11/20/2008 5:44pm Page 344

344 Chapter 7 ■ Contact Mechanisms: How to Get in Touch

More difficult to manage because different types of contact mecha-

nisms are modeled using different structures. Although this pattern

offers the benefit of being more specific than the level 3 and level 4 pat-

terns, this is also a disadvantage because each type of contact mechanism

may have different data model structures and may need to be handled

differently. Thus, there is not a consistent way of managing contact

mechanisms, and each type of contact mechanism may require d iffer-

ent data structures, rules, and routines. Thus, it may be more costly and

difficult to manage contact mechanisms with this pattern than by using

a common, consistent structure for contact mechanisms, such as the ones

in the level 3 or level 4 patterns.

When other entities are related to contact mechanisms, there are sev-

eral places to look (several entities for contact mechanisms), and this

can result in more complexity in systems development. Contact mecha-

nisms are referenced together frequently, and when you model different

types of contact mechanisms in their own entities, it makes it more dif-

ficult to answer questions like: ‘‘What are all the ways to contact this

person?’’ or ‘‘What are all the contact mechanisms for an order?’’

Synopsis

The Level 2 Contact Mechanism Pattern is a much more flexible pattern